Microphone attachment for telephones.



H. W. CHRISTENSEN, MICROPHONE ATTACHMENT FOR TBLEPHONES.

APPLIUATION FILED MAR. 19, 1913.

Patented Sept. 15,1914..

THE NORRIS PETERS (20.. PHOTO-LITHQ. WASHINGTON. D. C.

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To all whom it may concern:

Be it known that T, HANS W. CHRISTEN- SEN, citizen of the United States, and a resident of Boston, county of Sufl'olk, State of Massachusetts, have invented an Improvement in Microphone Attachments for Telephones, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to telephones, and more particularly to a means of increasing the transmitting or receiving power.

The object of my present invention is to provide a microphone attachment which can be easily, quickly, and readily secured to any existing telephone transmitter, or receiver, and which will aid in the transmission of tones over long distances, or will enable whispered tones to be readily heard.

In the development of the telephone, it has frequently been necessary to provide means to increase the vibrations of the receiving and transmitting diaphragms, and this has heretofore been accomplished by enlarging the diameter as well as to increase the delicacy of the interior arrangement of the transmitter and receiver. My microphone attachment enables an increased eflect of the voice to be transmitted to the transmitting diaphragm particularly, as well as a more resonant effect from the receiving diaphragm to the ear. To this end, I provide an attachment for the flaring end of the mouthpiece of the transmitter, comprising a thin metallic vibratory plate, which will be preferably secured to the mouthpiece by a non-vibratory metallic ring of sufiicient strength and rigidity to hold the thin plate firmly in position. I preferably make the contact between the thin vibratory plate and the mouthpiece air-tight, by means of any suitable pressure or adhesive substance, and therefore secure greater efiiciency in the op eration of my device. The thin vibratory plate will thus act as a microphone attachment to increase the effect of the voice due to the flaring form of the mouthpiece, as the tones are transmitted through the air to the regular vibratory diaphragm of the transmitter. By confining the air within the mouthpiece substantially air-ti ht, I am enabled to secure an added efficiency.

Other novel features of the invention, combinations of parts, and details of con Specification of Letters Patent.

Application filed March 13, 1913-.

' usual manner.

Patented Sept. 15,- 1914.

Serial R 0. 755,307.

struction, will be hereinafter more particularly pointed out and claimed.

Referring to the drawings, wherein a preferred embodiment of my invention is illustrated, Figure 1 is a view of an ordinary transmitter, being shown partly in section, iwith my microphone attachment applied thereto; Fig. 2 is a front view; and Fig. 3' is a view on the line 33 of Fig. 1.

A telephone transmitter of ordinary and well-known form is illustrated at 1, with a portion of the outer shell broken away to show the diaphragm 2, this transmitter being pivotally mounted on a support 3, as is customary. The transmitter is provided with a flaring mouthpiece 5, having its inner" end threaded into the face of the" shell 1, and with a plurality of recesses 6 in the side edges and a plurality of holes 7 in the To the flaring end of the mouthpiece I apply my attachment, comprising a very thin metallic plate 8, which is preferably of appropriate size and diameter to rest upon the extreme outer diameter and portion of the mouthpiece 5. A circular ring 9 is provided to hold the thin plate 8 in engagement with said mouthpiece 5, and is formed with a flange 10 engaging the top surface of the plate 8, and a depending flange 11 which bears on the outer and inwardly inclined surface of the rim of the mouthpiece, said flange 11 being correspond ingly inclined so as to retain both the ring 9 and the plate 8 in assembled position on the mouthpiece 5. The ring 9 could be sprung or snapped into position. Preferably I make this attachment air-tight, by aflixing a layer of glue or suitable adhesive, as indicated at 12, between the under surface of the plate 8 and the mouthpiece 5, or in any other suitable or desirable manner. The recesses 6, affording open communication between the outer air and that within the transmitter, I prefer to close and therefore provide a band or ring 13, which may also be made substantially air-tight, either by pressure or by the provision of adhesive means between its surface and that of the mouthpiece, wherein such recesses 6 are absent, since in the telephone receivers to be applied to the ear, such a band 13 is unnecessary.

The flaring form of the mouthpiece 5 together with the fact that the air contained therein. is substantially confined, enables the volume of the vibrations of the thin metallic plate 8 to be substantially increased, as such vibrations are transmitted from the plate 8 to the main diaphragm 2, as will be readily understood.

My invention also secures the advantages of a sanitary covering for telephone transmitters and similar instruments; the metal lic plate being preferably nickeled or highly finished can be quickly wiped off or cleaned,

and is substantially indestructible, While the entire attachment can be easily removed or readily applied.

It will thus be seen that I have provided a simple and eficient microphone attachment which can be readily applied to any existing telephone, and which greatly increases the distance carrying capacity of the voice, rendering the vocal tones much more audible at great distances than without such attachment. Furthermore, by having this microphone attachment, telephonic conversations can be carried on in whispered tones, practically inaudible to other persons in the same room, but being transmitted fully, clearly, and distinctly through the telephone.

A further advantage of my attachment is that the ordinary extraneous sounds, noises, and the like, usually so annoying and interrupting during telephone conversations, are very materially prevented and eliminated, not reaching the delicate main diaphragm 2 of the instrument.

Having described my invention, What I claim as new and desire to secure by Letters Patent is:

A microphone attachment for telephone, transmitters having a flaring mouthpiece and an air passage at the base of said mouthpiece comprising a thin metallic vibratory diaphragm, a non-vibratory rim having oppositely disposed flanges to engage said diaphragm and the mouthpiece of a tele-' phone, in combination with a band to seal the air passages between the mouthpiece and the shell of the transmitter.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

HANS W. CHRISTENSEN.

Witnesses:

JAMES R. HODDER, EDW'ARD MAXWELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patent; Washington, D. G." 

